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Study on acquisition of bacterial antibiotic resistance determinants in poultry litter
Dhanarani, T. Sridevi,Shankar, C.,Park, J.,Dexilin, M.,Kumar, R. Rajesh,Thamaraiselvi, K. Elsevier 2009 Poultry science Vol.88 No.7
<P>Antibiotic resistance and the mode of transmission were investigated in bacteria isolated from poultry litter. Total aerobic heterotrophic bacteria were screened and identified for their resistance to different antibiotics such as ampicillin, streptomycin, erythromycin, tetracycline, chloramphenicol, kanamycin, tobramycin, and rifampicin. The distribution of bacteria found in the litter was Staphylococcus (29.1%), which was the predominant group, followed by Streptococcus (25%), Micrococcus (20.8%), Escherichia coli (12.5%), Salmonella (8.3%), and Aeromonas (4.1%). Fifty percent of these isolates were susceptible to ampicillin, 57% to erythromycin, 25% to tetracycline, 4% to chloramphenicol, 40% to kanamycin, 75% to streptomycin, 54% to tobramycin, and 4% to rifampicin. Three randomly selected isolates representing Staphylococcus, Streptococcus, and Micrococcus were examined for plasmids, and plasmid-curing and plasmid-induced transformation studies were conducted. Streptococcus and Micrococcus harbored a plasmid of 4.2 and 5.1 kb, respectively, whereas Staphylococcus did not harbor any plasmids. Plasmids were cured in Streptococcus and Micrococcus at a concentration of 75 and 100 microg/ mL of acridine orange, respectively, and transformation of 4.2- and 5.1-kb plasmids isolated from the Streptococcus and Micrococcus to plasmid-free E. coli DH5alpha strain was possible. In conjugation experiments, the antibiotic resistance profiles of transconjugant cells were found to be the same as the donors with the exception of Staphylococcus. The results of this study suggest that transformation and conjugation could be an important mechanism for horizontal gene transfer between bacteria in poultry litter. An understanding of the mechanism and magnitude of resistance gene transfer may provide a strategy to reduce the potential for dissemination of these genes.</P>
A note on vertex pair sum $k$-zero ring labeling
Antony Sanoj Jerome,K.R. Santhosh Kumar,T.J. Rajesh Kumar 한국전산응용수학회 2024 Journal of applied mathematics & informatics Vol.42 No.2
Let $G=(V,E)$ be a graph with $p$-vertices and $q$-edges and let $R^{\circ}$ be a finite zero ring of order $n$. An injective function $f:V(G)\to \{r_1,r_2,\ldots,r_k\}$, where $r_i\in R^\circ$ is called vertex pair sum $k$-zero ring labeling, if it is possible to label the vertices $x\in V$ with distinct labels from $R^{\circ}$ such that each edge $e=uv$ is labeled with $f(e=uv)=[f(u)+f(v)] \pmod n$ and the edge labels are distinct. A graph admits such labeling is called vertex pair sum $k$-zero ring graph. The minimum value of positive integer $k$ for a graph $G$ which admits a vertex pair sum $k$-zero ring labeling is called the vertex pair sum $k$-zero ring index denoted by $\psi_{pz}(G)$. In this paper, we defined the vertex pair sum $k$-zero ring labeling and applied to some graphs.